“She calls him ‘Satan,’ ” snipes a pal close to the family. “Mandy even talks to strangers about how much she hates him.”

Selena has since found love with The Weeknd and is hoping her mother moves on from the “Jelena” saga, too.

“Selena told her to take the high road, but Mandy refuses,” adds the friend. “She says it’s what Justin deserves for making Selena — and their family — miserable for years. Mandy is such a sweet lady, but Justin is on her bad side forever. And she likes everyone!”